Laserfiche WebLink
<br />. <br /> <br />11. 03 <br /> <br />. <br /> <br />. <br /> <br />e <br /> <br />e <br /> <br />e <br /> <br />required for drainage with a minimum slope of one-half <br />(1/2) of one (1) per cent. <br />DRAINAGE AND STORM SEWERS. <br />Adequate drainage shall be provided within the limits of the <br />subdivisions. The protection of adjoining property will be <br />considered in the review of plans submitted. <br />1. Size: Sizing of inlets, storm sewers, outfalls, culverts, <br />and drainage ditches will be based on the following: <br />(a) Design Storm: The design storm will be based <br />on rainfall intensity-frequency data published <br />by the Department of Agriculture by David L. Yarnell. <br />Interior drainage system will be designed for a <br />storm with a frequency of occurrence of onee in <br />five years. The intensity of a 60 minute rainfall <br />on this frequency is 2. 80 inches. Major drainage <br />ditches and structures will be designed for a storm <br />with a frequency of occurrence of once in twenty-five <br />years. The intensity of a 60 minute rainfall on this <br />frequency is 3. 75 inches. <br />(b) Runoff Computations: To determine the runoff rates <br />for the various areas, the standards rational method <br />will be used, utilizing the formula Q -=- CIA, where <br />Q ~ rate of runoff in cubic feet per second, C = runoff <br />coefficient, 1= rainfall intensity for the particular <br />duration in inches per hour, and A = the drainage <br />area in acres. Drainage areas will be arrived at <br />by considering location of high and low points on <br />street grades, drainage divides in the area, and <br />general configuration of existing and finished grades. <br /> <br />,:26 <br />